PROJECT SUMMARY/ABSTRACT The overall goal of this K01 Mentored Research Scientist Development Award is to determine the relationships between high-THC cannabis product use, adverse effects, and digital health information exchange by combining mixed methods analysis of online forum conversations and original qualitative interview and quantitative survey data collection. Use of emerging high-THC cannabis products including edibles and concentrates may result in too much unintended THC intake and potentially adverse effects. At the same time, these new products do not typically involve combustion and inhalation of related byproducts (as smoked cannabis does) and so may be perceived as safer. In this evolving era of cannabis use, new and experienced cannabis users are turning to online venues to access peer-generated information and to share their experiences. The training goals of the proposed project are to develop expertise in mixed methods analysis of text data and pharmaco-epidemiology and to gain experience with digital health information exchange and user-centered study design strategies. The Specific Aims are to: (Aim 1) Identify gaps in knowledge regarding high-THC cannabis product use by applying text analysis to questions and experiences extracted from a dataset of user generated content posts an online cannabis and opioid communities from 2010 through 2018; (Aim 2) Describe motivations and contexts for using high-THC cannabis products and facilitators and barriers to finding online health information by conducting in-depth interviews with cannabis industry key informants (N=20) and with high-THC cannabis using adults (N=20); (Aim 3) Determine the relationships between emerging patterns of high-THC cannabis product use and adverse effect profiles, other substance use, and digital technology use by conducting an online survey (N=2000) with a geographically diverse U.S. sample of novel cannabis product-using adults. The proposed research program and training will support the candidate?s development into an independent investigator at the rapidly developing intersection of digital health and substance use research. This project and training plan will provide pilot data for a future proposal to develop and test a digital health resource for minimizing adverse effects associated with high-THC cannabis use.